1. Field of the Invention
The present invention relates to heal exchangers, and more specifically to heat exchangers used in a refrigeration or air conditioning system.
2. Description of the Related Art
A heat exchanger is a device used to transfer heat from a fluid on one side of a barrier to a fluid on the other side without bringing the fluids into direct contact. Heat exchangers are typically used in refrigeration systems and often take the form of a gas cooler, condenser, or evaporator.
A conventional refrigeration system including a coil and fin type heat exchanger is schematically illustrated in FIG. 1. Also shown in the schematic illustration of FIG. 1 is a compressor 6, evaporator assembly 8 and fan 18. Heat exchanger 10 generally includes fluid conduit 12 having a generally serpentine structure that includes a series of bends 14 interconnecting a series of parallel straight lengths of the conduit. Fluid conduit 12 extends through a plurality of heat exchange elements 16 such as flat, heat transfer fins. Heat exchange elements 16 are substantially perpendicular to the longitudinal axis of folded conduit 12. Fan 18 of the refrigeration system is positioned to generate an airflow in a direction indicated by arrows 17 that, in turn, induces airflow through the airflow passages defined by adjacent elements 16 as indicated by arrows 19 to thereby remove heat from the heat exchanger.
Oftentimes, the heat exchanger forming the condenser of a refrigeration system will be mounted along the edge of a rectilinear baseplate with a fan mounted thereto and generating an air flow perpendicular to the parallel straight lengths of the conduit and parallel to the airflow passages defined by fins mounted on the straight lengths of the conduits at a perpendicular angle. In the system shown in FIG. 1, heat exchanger 10 is mounted at an angle relative to the edges of the base plate and fan 18 generates an airflow in direction 17 that is at an angle to the direction defined by the airflow passages formed between adjacent heat exchange elements 16 that are mounted on the heat exchanger conduit at a perpendicular angle. In the system illustrated in FIG. 1, the orientation of heat exchanger 10 and the air flow passages extending therethrough relative to the direction of the airflow 17 generated by fan 18 has a negative impact on the quantity of air passing through heat exchanger 10 and, consequently, the ability of the air to remove heat from the heat exchanger.
The present invention provides a heat exchanger for use in a refrigeration system including a fluid conduit having a plurality of heat transfer elements mounted thereon at a non-perpendicular angle to the longitudinal axis of the conduit. An airblower or fan may also be included in the system and the alignment of the positioning of heat exchange elements is coordinated with the airflow generated by the airblower to enhance the quantity of air passing through the heat exchanger and thereby improving the performance of the heat exchanger.
The invention comprises, in one form thereof, a heat exchanger assembly including a compressor, a heat exchanger and an airblower. The heat exchanger has a fluid conveying conduit in fluid communication with the compressor and a plurality of heat exchange elements thermally coupled with a first heat exchanging segment of the conduit, each of the elements having at least one heat transfer surface. The airblower is mounted in a first position relative to the heat exchanger wherein the airblower generates an airflow in a first direction. The first heat exchanging segment of the conduit substantially extends longitudinally in a second direction with the first direction defining a non-perpendicular first angle with the second direction. The heat transfer surfaces define at least one airflow passage extending through the heat exchanger in a third direction, the third direction defining a non-perpendicular second angle with the second direction, the second angle and the first angle having a difference of no greater than approximately 30 degrees.
The heat exchanger assembly may be configured wherein the first direction defined by the airflow generated by the airblower and the third direction defined by the airflow passage through the heat exchanger are substantially parallel. The first heat exchanging segment of the conduit may have a generally serpentine shape and include a plurality of bends interconnecting a plurality of substantially parallel lengths of the conduit with the lengths extending in the second direction and being vertically spaced and thermally coupled to the heat exchange elements.
The conduit may also include a second heat exchanging segment having a second generally serpentine shape and including a second plurality of bends interconnecting a second plurality of substantially parallel lengths of the conduit extending in a fourth direction. The second lengths are vertically spaced and thermally coupled to a second plurality of heat exchange elements thermally coupled with the second lengths. Each of the second plurality of heat exchange elements have at least one second heat transfer surface wherein the second heat transfer surfaces define at least one second airflow passage extending through the second heat exchanger segment in a fifth direction and the fourth and fifth directions form a non-perpendicular third angle. In an assembly including two heat exchanging segments, the second and fourth directions respectively defined by the first and second heat exchanging segments of the conduit may define an angle and the third and fifth directions defined by the airflow passages extending through the first and second heat exchanging segments may each be substantially parallel to the first direction defined by the airflow generated by the airblower.
The plurality of heat exchange elements may be formed by a plurality of substantially planar fins wherein each of the fins defines first and second heat transfer surfaces disposed on opposite sides of the fin and wherein the fins are disposed substantially parallel to one another.
The invention comprises, in another form thereof, a system having a base plate, compressor, heat exchanger and airblower. The compressor is mounted to the base plate and has a discharge port for discharging compressed fluid. A fluid conveying conduit is in fluid communication with the discharge port of the compressor. The heat exchanger is mounted to the base plate and has a plurality of heat exchange elements thermally coupled with a first heat exchanging segment of the conduit, each of the elements having at least one heat transfer surface. The airblower is mounted to the base plate wherein the airblower generates an airflow in a first direction. The first heat exchanging segment of the conduit substantially extends longitudinally in a second direction with the first direction defining a non-perpendicular first angle with the second direction. The heat transfer surfaces define at least one airflow passage extending through the heat exchanger in a third direction with the third direction defining a non-perpendicular second angle with the second direction, the second angle and the first angle having a difference of no greater than approximately 30 degrees.
The first heat exchanging segment of the system may form a condenser and the fluid compressed by the compressor and discharged into the conduit may be a combustible refrigerant. The base plate may have outer perimetrical edges defining a substantially rectilinear shape wherein the second direction defined by the first heat exchanging segment defines a non-perpendicular angle with the edges and the first heat exchanging segment is positioned proximate the compressor so that airflow generated by the airblower impinges upon both the first heat exchanging segment and the compressor.
Alternatively, the base plate may have a plurality of outer perimetrical edges wherein first and second heat exchanging segments are positioned proximate at least one of the edges and the first and second heat exchanging segments respectively have first and second lengths that cumulatively define a length greater than a length of the at least one proximate edge.
The invention comprises, in another form thereof, a method of transferring thermal energy including circulating a fluid through a circuit having a compressor operably coupled thereto wherein circulation of the fluid includes conveying the fluid through a conduit having a heat exchanging segment; mounting a plurality of heat exchange elements on the heat exchanging segment of the conduit, each of the heat exchange elements having a heat transfer surface, wherein the mounted heat exchange elements are thermally coupled with the conduit and the heat transfer surfaces define at least one airflow passage, the airflow passage extending in a direction that forms a non-perpendicular angle with the heat exchanging segment of the conduit; and generating an airflow at a non-perpendicular angle to the heat exchanging segment of the conduit and wherein the airflow passes through the at least one airflow passage and exchanges thermal energy with the heat transfer surface.
The airflow generated in such a method may be in a direction that is substantially parallel to said at least one airflow passage. The airflow generated in such a method may also impinge upon a compressor operably coupled to the circuit.
One advantage of the present invention is that by aligning an airflow passage extending through a heat exchanger and defined by heat transfer surfaces at a non-perpendicular angle relative to the longitudinal direction of the heat exchanging segment of a fluid conduit, the present invention provides for a higher density and more compact refrigeration or condenser configuration wherein the heat exchanger is positioned in closer proximity to the other components and configured to take advantage of the available space between the other components.
This repositioning of the heat exchanger may require that the airflow generated by the blower intersect the longitudinal direction of the heat exchanging segment of the conduit at a non-perpendicular angle. By defining an airflow passage through the heat exchanger with the heat transfer surfaces that is also non-perpendicular to the longitudinal direction of the conduit, the airflow passage through the heat exchanger may more closely conform to the direction of the airflow generated by the blower and thereby relatively enhance the performance of the heat exchanger in a compact system configuration.
Another advantage of the present invention is that by facilitating the design of relatively compact condenser and refrigeration systems, the lengths of the fluid conduits interconnecting the various components of the system may be reduced thereby reducing the internal volume of the system and facilitating the reduction of the total refrigerant charge required by the system. Such a reduction of the refrigerant charge is particularly advantageous when using combustible refrigerants such as those containing hydrocarbons or ammonia.
Yet another advantage of the present invention is that it provides greater flexibility in the placement of the heat exchanger relative to the other components of the refrigeration system while minimizing or preventing negative impacts on the performance of the heat exchanger that may be associated with the alternative placement of the heat exchanger. The greater flexibility in placement of the heat exchanger also provides benefits such as greater flexibility in cabinet design. Additionally, the heat exchanger may be positioned in proximity to a compressor wherein the airflow generated by the blower impinges upon the compressor as well as the heat exchanger thereby providing enhanced cooling of the compressor and system performance. Such a configuration may also involve the use of two heat exchanger segments which at least partially surround the compressor.
Still another advantage of some embodiments of the present invention is that it provides for the use of two heat exchanging segments positioned proximate an edge of the base plate on which the system is mounted and at an angle to the proximate edge whereby the cumulative lengths of the two heat exchanging segments is greater than the length of the proximate edge. If such segments were replaced by a conventional heat exchanger extending parallel to the proximate edge, to have the same length of conduit within a heat exchanger of the same height would require the heat exchanger to have a greater depth to provide additional rows of conduits. When an excessive number of such heat exchanger conduit rows are added, the performance of the heat exchanger may be degraded because the air passing across the last rows of conduits will have a reduced temperature differential with such conduits due to the thermal energy already transferred to the air by the initial rows of the heat exchanger. By providing for the angled positioning of two heat exchanger segments, the present invention facilitates the avoidance of such inefficient heat exchanger designs.